Slight head shake

[WuzzaCBXRider]

Under 60 mph if I take my hands off the grips I get a tiny shake. The last bike I had that head shake was my 79 CBX. All it took to fix it was to (very) slightly tighten the big top nut. Bike has over 83,000 and has never done it before. Suppose that’s the problem?

 

[Bumblebee]

Under 60 mph if I take my hands off the grips I get a tiny shake. The last bike I had that head shake was my 79 CBX. All it took to fix it was to (very) slightly tighten the big top nut. Bike has over 83,000 and has never done it before. Suppose that’s the problem?

Which bike are you referring to?

Slightly worn steering head bearings or the collar nuts need to be either tightened or loosened, tire pressures or uneven wear...or depending on the bike the steering damper could be in need of maintenance.....

 

[sixpack577]

Bar shake on decel is steering neck bearings.
You can try torquing the nut, but if it's in spec, the bearings will need replaced.
(You can also use a regular 6 point metric socket on that specialty nut, and if I remember correctly, it is the same 36mm as the rear axle that fits it).
Bad fork alignment or bad tire balance, as well as low psi or worn tire issues would be present on acceleration as well.
With over 80k miles on the bike, I would replace the bearings.